1)t=0 前,u1=0,Uc(0)=0;
2)t=∞ 后,I2=0.5U1,U1=I1*R1;Is = I1 + I2;
Uc(∞)= U1 - I2*R2 ;
3)运用戴维南等效电阻法求出时间常数中的电阻值;
I = I' + I'' , U1 = I' *R1 , I'' = 0.5U1 ; 那么等效电阻 R = U/I ;
4)代入全响应公式,得 Uc(t),那么
U1(t) = Uc(t) + I2*R2 = I1*R1 ;Is = I1 + I2; I1=U1(t)/R1
U1(t) = Uc(t) + (Is - I1)*R2 = Uc(t) + (Is - U1(t)/R1)*R2;
U1(t) = (Uc(t) + Is*R2)*R1/(R1+R2) ;